Oil cooling system for internal combustion engines



United States Patent 1 1 3,550,725

[72] Inventor Emil Alois Hegglin, 246, General-Wille [56] References Cited SPEEEQ, Feldmeilen, Zurich, Switzerland UNITED STATES PATENTS 1 1 PP 726,484 1,906,538 5/1933 Church 184/6X 1 1 PM May 3 33 1,078,919 11/1913 Hall l23/196X 1 1 3 1 1,318,706 10/1919 Talbot 184/104 21 Prwmy Feb-8,1968 1,666,485 4/1928 Bradford 184/104 Germany 1,761,686 6/1930 Schloerb 184/104 1 Flo-B65259 2,134,778 11/1938 Clarke l65/35X 2,291,637 8/1942 Kohlmanm. 165/35 OIL COOLING SYSTEM FOR INTERNAL 2,578,059 12/1951 Graham 165/176X COMBUSTION ENGINES Primary Examiner-Manuel A. Antonakas 4 Claims, 9 Drawing Figs. Attorney- Ward, McElhannon, Brooks & Fitzpatrick [521 [1.5. CI 184/104; 123/196 [51] int. Cl F01m 5/00,

F16n 39/02 ABSTRACT: Oil cooling system for internal combustion en- [50] Field of Search 184/104B, gines having an oil pump and a heat exchanger connected to 6F; 165/51, 176; 12 3/196AB the suction side of the pump.

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OIL COOLING SYSTEM FOR INTERNAL COMBUSTION ENGINES The invention relates to an oil cooling system for internal combustion engines having aheat exchanger which is located in an oil circuit comprising the oil reservoir of the engine and an oil pump.

Engine oil is only capable of acting as a lubricant up to a certain temperature of the order of 140 C. At higher temperatures damage to the engine occurs. Great care and expense is incurred regarding the cooling of the combustion chambers, cylinders and cylinder heads in present day engines, whereas, apart from a few exceptions, too little attention is paid to the oil-cooling system. Not infrequently, therefore surprising damage of various kinds occurs, particularly in sports driving, long distance driving, pass driving, in hot weather, etc. An attempt has been made to combat this drawback generally by enlarging the part of the oil sump subjected to air currents, whereby the engine oil very often remains too cold for a lengthy time, particularly in winter.

It is known in various air-cooled petrol and diesel engines to have built-in progressive oil coolers in the cooling air current. These generally require, however, more blower energy than is necessary to meet the temperature requirements of the cylinder and combustion chambers because the system is designed from the point of view of the greatest possible safety.

The object of the present invention is to remove these drawbacks and to provide an effective oil-cooling system with which it is possible to reduce the forced air-cooling output in favor of increased engine performance; or to increase the engine performance with the same size cooling system. This is attained according to the invention in that the heat exchanger for the oil-cooling system has one or more circulation chambers and is connected to the suction side of the oil pump.

By circulation chambers is to be understood not a single large chamber as, for example, the oil sump in which the oil undergoes an almost insignificant flow; but rather chambers in which the oil flow is guided in quite a definite manner at not inconsiderable speed, i.e. chambers which form a flow channel of relatively small flow cross section. The present oil-cooling system makes it possible to utilize for cooling the oil considerable quantities of air passing by hitherto unused under the vehicle at a speed of about km. per hour so that a driven blower is not necessary.

The heat exchanger can thereby lie in the oil circuit comprising those points in the engine to be lubricated. It is however possible to arrange it in a special cooling circuit which is disposed next to the oil circuit enclosing the lubrication points and like the oil circuit is connected to the oil reservoir of the engine. The heat exchanger may be advantageously fixed directly on the bottom or sidewall of the oil reservoir so that its outlet enters directly into the oil reservoir and is connected inside the reservoir to the suction pipe of the oil pump leading into the reservoir.

The arrangement according to the invention of heat exchanger in the form of a circulating system on the suction side of the oil pump offers the advantage that the oil at the lubricating points of the engine which may have foamed up can be skimmed because the gas deposits contained in the oil foam in the oil-cooling system according to the invention, after cooling, move back towards the oil current into the oil reservoir which in the known oil-cooling systems in which the heat exchanger lies on the pressure side of the oil pump, is not possible. Thereby also a substantially lesser dirtying of the oil is ensured. In the oil-cooling system according to the invention the temperature buildup in the oil is efi'ected in addition substantially more practically than in a cooling system in which the heat exchanger is located on the pressure side of the pump. It furthermore reduces the price of manufacture and simplifies the operation and in addition also renders in a simple manner a self-cleaning of the cooler by the wind during travel.

Further details and advantage of the cooling system according to the invention will become apparent from the following description of some embodiments of the invention given by way of example only. The description will be given with reference to the accompanying drawings in which:

FIG. 1 and 2 show diagrammatically two different embodiments of cooling systems according to the invention;

FIG. 3 is a plan view of one construction of a heat exchanger suitable for use in a system according to the invention;

FIG. 4 is a section through the heat exchanger taken on line lV-IV of FIG. 3 and showing the heat exchanger fixed on an oil sump;

FIG. 5 is a plan view of another heat exchanger according to the invention;

FIG. 6 is a section through the heat exchanger taken on line Vl-Vl of FIG. 5;

FIG. 7 is a view of the inlet and outlet of the heat exchanger of FIG. 5, from below, with the cover removed;

FIG. 8 is a section through the inlet and outlet of the heat exchanger taken on line VIII-VIII of FIG. 7; and

FIG. 9 is an enlarged fragmentary view of the heat exchanger with a portion broken away to illustrate a port controlled by a temperature responsive valve.

In the oil-cooling system shown diagrammatically in FIG. I, the heat exchanger 1 is disposed in the oil circuit comprising the lubricating places of the engine 2. This oil circuit proceeds from the oil sump 3 forming the oil reservoir to the bottom of which an outlet pipe 4 leading to the heat exchanger 1 is connected. The outlet 5 of the heat exchanger 1 passes through the floor wall of the oil sump 3 and within the oil sump is connected to the suction pipe 6 of the oil pump 7 which pumps the oil to those points or places of the engine 2 to be lubricated, and from which it flows back via the return flow pipe 8 into the oil sump 3.

In the construction of the oil-cooling system according to the invention illustrated in FIG. 2 the heat exchanger I is located in its own cooling circuit which is disposed next to the usual oil circuit 6, 7, 8 incorporating those places of the engine 2 to be lubricated and is also connected to the oil sump 3. This cooling circuit is formed by a pipe 4 to the heat exchanger 1 connected to the bottom of the oil sump 3 and a return pipe 9 leading back into the oil sump 3 in which a separate pipe is connected to the oil pump 10. In both constructions according to FIGS. 1 and 2, therefore, the heat exchanger 1 according to the invention is located on the suction side of the pumps 7, 10 circulating the oil to be cooled. Likewise in both cases the heat exchanger 1 is disposed directly on the under the underside of the oil sump so that it is subjected to the air flowing during travel under the motor vehicle which effects the cooling of the oil in the heat exchanger. It would of course b also be possible to carry out the cooling of the oil in the heat exchanger by means of a liquid cooling medium. In this case however a separate circuit for this cooling liquid would be necessary as well as a further heat exchanger, lying preferably in the airflow during travel, in which the cooling liquid would be brought to the necessary low temperature.

In the construction illustrated in FIGS. 3 and 4, the heat exchanger for the oil to be cooled consists of a spirally coiled pipe 11 made of a heat conducting material. The coiled pipe leads with a bent inlet end 12 into an inlet chamber 13 which is fixed on the underside of the oil sump 3' in the area of the opening 14 for the oil outlet by means of screws or the like. The outlet end portion 15 of the coiled pipe 11 extends with suitable bending through the inlet chamber 13 and the oil outlet opening 14 and terminates in the oil sump 3 at a short distance above the bottom of the sump. At this outlet end 15 of the coiled pipe 11 of the heat exchanger the suction pipe 6 of the oil pump 7 is so configured that an annular gap 16 is formed between it and the end 15 of the coiled pipe 11. Actually, the two pipes are shown to be of different diameters and overlapping. This annular gap serves at the beginning of the operation of the oil pump to ensure an immediate oil circulation over the lubrication places of the engine and in fact lOlUZl 0402 even when the oil in the heat exchanger is so cold, for example, due to standing of the engine in winter, that it is driven only very slowly through the heat exchanger.

In this case therefore oil from the oil sump 3 is drawn through the annular gap 16 by the pump 7, bypassing the coiled pipe 11, and passes directly into the suction pipe 6. Thus, an immediate supply of oil to the lubrication places of the engine 2 is ensured. As suction of oil through the annular gap 16 is not absolutely ensured with low oil level in the oil sump 3, the outlet end of the coiled pipe 11 inside the inlet chamber 13 has additional inlet bores 17 through which likewise oil can pass bypassing the coiled pipe 11 and flowing directly into the suction pipe of the oil pump 7. As shown in FIG. 9, these openings 17 can be controlled, for example, thermostatically by means of a bimetallic valve 17a responsive to the oil temperature. Their passage cross section can thus be varied so that they are, when the oil is cold, substantially open and, when the oil is warm, more or less closed.

As with the conventional oil sumps of motor vehicles, the suction pipe 6 of the oil pump 7 is located directly above the outlet opening 14 of the oil sump, so that with the embodiment of the oil-cooling system illustrated a reconstruction of the suction pipe and the oil sump is not necessary. The outlet end 15 of the coiled pipe 11 of the heat exchanger overlaps the lower end of the suction pipe 6 of the oil pump and the inlet 13 of the heat exchanger contacts directly the bottom wall of the oil sump 3 and can be fixed to this. Since thereby the inlet chamber 13 is located directly under the oil outlet opening 14, passage of the oil into the inlet chamber 13 and from there into the coiled pipe 11 is ensured automatically. In order to facilitate the location of the heat exchanger with its outlet end 15 on the suction pipe 6, the outlet end can be widened conically.

The inlet end 12 of the coiled pipe 11 leads at a distance above the bottom of the inlet chamber 13 into this chamber. Thereby the entry of impurities into the oil circuit is avoided. An oil filter can therefore be dispensed with. The inlet chamber 13 is also provided on its bottom with an opening capable of being closed by a screw 18 which, with the heat exchanger fixed on the sump 3, is intended instead of the opening 14 of the coil sump 3 for the oil outlet. This closure screw 18 may contain a magnet core which attracts impurities in the oil and permits their easy removal when changing oil.

As the heat exchanger 1 in this construction is fixed on the sump 3 only in the area of the oil outlet opening 14 of the oil sump 3 by means of a few screws, it can be removed without a great deal of effort for the purpose of cleaning it. The work required for this is not greater than the cleaning of the oil filter necessary hitherto at the inlet end of the suction pipe of the oil um p ln the construction shown in FIGS. 5 and 6, the heat exchanger consists of a series of cooling pipes 19 disposed parallel to one another and which are connected at their two ends to connection pipes 20, 21. One connection pipe 20 is divided by a separating wall 22 into a distributor section 23 and collecting section 24. A feedpipe 25 leads into the distributor section 23 while a leadoff pipe 26 is connected to the collecting section. The feedpipe 25 leads into a chamber 27 and the leadoff pipe 26 leads into a further chamber 28 which two chambers are disposed in a casing 29 and are separated by a separating wall 30. In this separating wall 30 are located bores 31 through which the two chambers 27, 28 are directly connected to one another. These bores have the same effect as the openings 17 in the heat exchanger according to FIGS. 3 and 4, namely oil to allow a quantity of still viscous oil to bypass the heat exchanger to come directly from the oil sump 3 into the suction pipe 6 of the pump 7 in order to avoid in this case also a temporary emptying of oil or a lack of oil at the lubrication places. The casing 29 is closed on its underside by a lid capable of being screwed on and off while on the side lying opposite the lid there is provided an annular fixing flange 33 by which the casing like the inlet chamber 13 in the construction according to FIGS. 3 and 4 can be screwed to the bottom wall of the oil sump 3. For this purpose, a series of bores 34 for receiving fixing screws or the like are provided. The chamber 28 is open on its top side like the inlet chamber 13 in the aforementioned construction so that the oil can enter through the outlet opening 14 in the oil sump 3 into this chamber 28 which is capable of being placed directly on this oil outlet opening. From this chamber 28 the oil comes via the feedpipe 25 to the pipes 23, 19, 21 and 24 of the heat exchanger and from there via the leadoff pipe 26 into the chamber 27 of the housing 29. This chamber 27 is on its upper side opposite the lid 32 provided with an outlet connection piece 35 which is capable of being inserted directly over the end of suction pipe 6 of the oil pump 7 located directly over the oil outlet opening 14 in the oil sump 3. Thereby the heat exchanger 1 is con nected to the suction side of the oil pump 7.

On one end of the connection pipe 21 of the heat exchanger according to FIGS. 5 to 8 there is located an opening closed by a closure screw 36 which like the lid 32 of the housing 29 can be used for the oil charge but also has a second opening for the rinsing of the pipe system of the heat exchanger.

Of course the heat exchanger according to FIGS. 3 and 4 as well as that of FIGS. 5 and 8 is to be used in the manner illustrated in FIGS. 1 and 2.

I claim:

1. An oil-cooling device for mounting below the oil reservoir of an internal combustion engine, said reservoir being in fluid flow communication with an oil pump which circulates oil through said reservoir and removes oil from said reservoir through a suction pipe extending into said reservoir, comprising: a heat exchanger, inlet means connecting said heat exchanger with said reservoir for permanently keeping said heat exchanger filled with oil, outlet means including a an outlet pipe in fluid flow communication with said suction pipe for directing oil to said suction pipe from said heat exchanger, said suction pipe also communicating with said reservoir to provide a direct oil connection between said reservoir and said pump whereby, depending upon its temperature and viscosity, a greater quantity of oil passes to said suction pipe from said reservoir either directly or through said heat exchanger, and means effecting communication between said outlet means and said reservoir whereby additional oil can pass to said pump directly from said reservoir.

2. A device according to claim 1, wherein said means effecting communication between said outlet means and said reservoir are bores located in said outlet pipe.

3. A device according to claim 1, wherein said means effecting communication between said outlet means and said reservoir define at least one opening in said outlet means, and wherein temperature responsive valve means valve means are provided operable to open or close said means effecting communication between said outlet means and said reservoir.

4. An oil-cooling device for mounting below the oil reservoir of an internal combustion engine, said reservoir being in fluid flow communication with an oil pump which circulates oil through said reservoir and removes oil from said reservoir through a suction pipe extending into said reservoir, comprising: a heat exchanger, inlet means connecting said heat exchanger with said reservoir for permanently keeping said heat exchanger filled with oil, outlet means including an outlet pipe in fluid flow communication with said suction pipe for directing oil to said suction pipe from said heat exchanger, said suction pipe also communicating with said reservoir to provide a direct oil connection between said reservoir and said pump whereby, depending upon its temperature and viscosity, a greater quantity of oil passes to said suction pipe from said reservoir either directly or through said heat exchanger, and a casing secured under an opening in the reservoir bottom and below said suction pipe, said outlet pipe extending up from said heat exchanger through said opening to said suction pipe, said casing being divided into a suction chamber and an inflow chamber by a separating wall having bores defined therethrough, said inflow chamber being in fluid flow communication with the oil in said reservoir and being connected to said inlet means, and said suction chamber being connected to said outlet pipe and being in fluid flow communication with said heat exchange means. 

